A ground loop is the
mechanism by which a geothermal system gathers the heat from the ground
and delivers it to the building (heating cycle) or takes the heat from the
building and releases it into the ground (cooling cycle)

Heat
Pumps

A heat pump is
nothing more than a refrigeration unit and contains the same basic
components found in a refrigerator

Sustainable development -Hydropower systems

hydropower

a system

to flow

to produce

the mechanical
energy

although

several

the ways

to produce
energy

to require

a large storage
reservoirs

the direct current
(DC)

the hydro turbine

the alternating
current (AC)

Cavitation
:

Noise or vibration causing damage to
the turbine blades
as a results of bubbles that form in the water as it goes through the
turbine.

Draft tube
:

a water conduit, which can be straight or curved
depending upon the turbine installation,

Head

Vertical change in elevation, expressed in either feet
or meters, between the head water level and the tail water level.

Flow :

volume of water, expressed as cubic feet or cubic
meters per second, passing a point in a given amount of time.

Headwater :

the water level
above the powerhouse.

Low Head :

Head of 66 feet or
less.

Runner

the rotating part of
the turbine that converts the energy of falling water into mechanical
energy.

Scroll case

a spiral-shaped
steel intake guiding the flow into the wicket gates located just prior to
the turbine.

Small hydro

Projects that
produce 30 MW or less.

Tailrace

the channel that
carries water away from a dam.

Tailwater

the water downstream
of the powerhouse.

Ultra low
head

Head of 10 feet or
less.

Wicket
gates

adjustable elements
that control the flow of water to the turbine passage.

Penstock :

a
closed conduit or pipe for conducting water to the powerhouse.

Sustainable development -Solar cells system

a solar cells
photovoltaic cell

a light energy

a moving parts

dependable

friendly

silent

the emission free

a suitable

a wavelength

a hit

a photovoltaic cell

the silicon

to convert

to transfer

a function

the photo generation

the electrical
energy

the photovoltaic
effect.

the field of
technology

the sunlight

the carriers

the electron

the light-absorbing
material

the solar modules

the photovoltaic
arrays

the grid

to generate

a device

the renewable
energy :

Particularly useful
in situations where electrical power from the grid is unavailable such as
in remote area power systems, Earth-orbiting satellites and space probes,
remote radiotelephones and water pumping applications.

Sustainable development -Solar water heater

a solar cells

a solar panel

a solar energy

the emission free

a suitable

a wavelength

a hit

to convert

to transfer

a device

a function

the field of
technology

the sunlight

the carriers

a solar water heater

a solar collector

a storage tank

solar absorber

a double walled
jacket

thermosiphonic flow

to be induced

a solar radiation

a valve

a liquid which
vapourises at a

prescribed
temperature

the light-absorbing
material

the solar modules

the renewable
energy :

Solar heating
systems are generally composed of solar thermal collectors, a fluid system
to move the heat from the collector to its point of usage, and a reservoir
or tank for heat storage and subsequent use. the systems may be used to
heat domestic hot water, swimming pool water, or for space heating.